Abstract: The mass flow simulation system of thin slab continuous casting and rolling process in Tangshan iron and steel company was developed by integrating the technologies of simulation, database, network, communication and computer. This system is composed of six subsystems:scheduling, steelmaking, refining, continuous casting, reheating and continuous rolling. The main work of the scheduling subsystem are:initializing simulation parameters, establishing produce schedule and real modifying. The main work of other subsystems are procedure simulating, parameters enacting and malfunction arising. This software can simulate the producing process so as to realize the reasonable joining and matching of all the procedures in the producing line. The scheduling plan can be established and modified on-line according to the real production conditions. The malfunctions can be disposed timely and flexibly.